1. Field of the Invention
The invention relates to a circuit breaking apparatus, in particular a multiphase circuit breaker, comprising a common quick trip mechanism which may be set and released by means of a local manual control member, a multiplicity of power circuits each comprising between two terminals a switch whose mobile contact is connected to said mechanism so as to be closed and opened thereby, detectors which react to over currents of different kinds in these circuits by causing tripping of said mechanism and, consequently, the automatic opening of the switches and an electromagnet which is associated with aid apparatus for causing remote controlled opening of the switches not causing tripping of said mechanism.
2. Description of the Prior Art
Such apparatus are widely used in particular in complex industrial installations where it is necessary to be able to supply, isolate or re-establish groups of machines in accordance with a hierarchy and sequentially when interruptions must be or have been made for carrying out certain tests or respectively following breakdowns, adjustments or overhauls; the use of such apparatus is in particular recommended in so called selective electric installations and particularly in those which are driven by programmable sequences.
From the patent PCT No. WO 83/02680 a protection apparatus is already known having the general above mentioned construction and in which the switch is opened in the remote controlled operating mode, through movement of the mobile contact.
In this apparatus, and although the quick trip mechanism is not released at the time of this operation, a certain number of parts which form it are however moved so that frequent operation by the remote control means may cause premature wear of the parts required for resetting the mechanism and so that the power of this electromagnet must be greater than that which would be strictly necessary for opening the switch. In addition, the armature of the electromagnet serving for effecting this remote controlled opening is connected to the manual control member so that operation thereof forces the operator to exert a greater force; finally, this apparatus may be reproached because of the risk it may present for the installation to be protected since, because the manual control has priority over the remote control, it is not possible to remotely prevent an uninformed person from repeatedly attempting to re-establish a faulty line or to supply a line with power on which other persons may be occupied at work of different kinds.
The invention consequently proposes providing a circuit breaker type protection apparatus having the general above mentioned construction but in which measures will be taken for overcoming the disadvantages which have just been mentioned.